Heat-developable photographic materials are known in the field of these techniques. Heat-developable photographic materials and processes therefor have been described in U.S. Pat. Nos. 3,152,904, 3,301,678, 3,392,020 and 3,457,075, British Pat. Nos. 1,131,108 and 1,167,777, and Research Disclosure, No. 17029, pages 9 to 15 (June, 1978).
Many different processes for obtaining color images have been proposed. The formation or bleach of dyes is performed in various processes and includes, for example, the following processes:
(1) formation of a dye by bonding of an oxidized product of a reducing agent which is formed upon the oxidation-reduction reaction between an organic silver salt oxidizing agent and a reducing agent with a coupler. PA1 (2) releasing of a diffusible dye by the reaction of a coupler having a diffusible dye as a releasable group with the oxidized product of a reducing agent described above. PA1 (3) releasing of a diffusible dye by the oxidation-reduction reaction between a silver salt of silver salt forming dye and a reducing agent. PA1 (4) formation of a dye by the oxidatio-reduction reaction between a leuco body of a dye or a precursor thereof and an organic silver salt oxidizing agent. PA1 (5) bleaching of a dye with a metal silver. PA1 (6) releasing of a diffusible dye by the oxidation-reduction reaction between an organic silver salt oxidizing agent and a dye releasing redox compound and the subsequent attack with a nucleophilic agent. PA1 Hexabenzoylsaccharose PA1 Heptabenzoylsaccharose PA1 m.p.: 181.degree. to 183.degree. C. PA1 m.p.: 189.degree. to 191.degree. C. PA1 m.p.: 144.degree.-149.degree. C. PA1 Yield: 5.2 g PA1 Yield: 17 g (76%) PA1 (b) is an acrylic acid ester; and PA1 (c) is acrylonitrile.
The process of (1) is described, for example, in U.S. Pat. Nos. 3,531,286, 3,761,270 and 4,021,240, Belgian Pat. No. 802,519, Research Disclosure, Vol. 139, No. 13946.
The process of (2) is described, for example, in Japanese Patent Application Nos. 71234/81, 93533/81 and 177611/81.
The process of (3) is described, for example, in Research Disclosure, Vol. 169, No. 16966.
The process of (4) is described, for example, in U.S. Pat. Nos. 3,985,565 and 4,022,617.
The process of (5) is described, for example, in Research Disclosure, Vol. 144, No. 14433, ibid., Vol. 152, No. 15227, U.S. Pat. No. 4,235,957.
The process of (6) is described, for example, in Japanese Patent Application Nos. 65391/81, 84164/81 and 157798/81.
The heat fusible compound according to the present invention is employed in the process of (6).
In the process of (6), an oxidation-reduction reaction occurs between a light-sensitive silver halide and a dye releasing redox compound in the exposed area and subsequently the oxidized product of the dye releasing redox compound is subjected to attack with a nucleophilic agent to release a dye. The dye released in diffusion-transferred into an image-receiving sheet and thus a color image is obtained.
However, the photographic material employed has a disadvantage that stability during preservation is poor and it is difficult to obtain a clear image. The stability during preservation used herein means stability of the photographic material during preservation before heat-development processing. That is, the photographic material has a drawback that the reaction for releasing a dye occurs during preservation thereof before heat-development processing and consequently, fog density and the maximum density are increased in an image obtained by the heat-development processing.